The human skin consists of epidermis, corium and tela subcutanea. The epidermis is classified into four layers, namely stratum corneum, stratum granulosum, stratum spinosum and stratum basale. The quantity of ceramides is lower in the stratum corneum of atopic dermatitis, dry skin and the skin of aged individuals. The ceramide content of the skin declines with increasing age (e.g. over 70 years old) with dry appearance in xerotic skin. In addition, there is a marked reduction in the amount of total ceramide in both lesional and non-lesional skin as compared to that of healthy individuals of the same age.
More than just a cosmetic problem, skin aging exposes individuals to significant health risks from infectious microorganisms, UV radiation, defective permeability to topical drugs, and increased susceptibility to contact dermatitis from environmental chemicals. The skin barrier is essential for protecting skin against physical stimuli, thermal challenge and ultraviolet radiation, chemical substances and microbial attack and preventing water loss. The skin needs to be at its functional best in order to properly function (i.e. regulate body temperature, synthesize optimal amounts of vitamin D, and provide critical sensory input from the environment). In vitro studies demonstrate that the moisture content of the stratum corneum is decreased with age. In maturing individuals, the stratum corneum is also susceptible to inflammation and infection. Aging skin also suffers from reduced structural integrity due to lower lipid content, mostly a lower proportion of ceramides. The decline of the ceramide content in aging human skin is possibly due to a decline in enzyme activity that helps to deliver ceramides in usable form to the skin. When aging skin's ability to make ceramides diminishes, as it inevitably does, increased ceramide intake becomes essential.
Synthetic and animal ceramide have been used as materials in cosmetic manufacture. However, it was discovered that Creutzfeldt-Jakob disease may be contracted from eating or using contaminated animal products, especially that of cattle.
What is needed in the art therefore is a safe and effective treatment for improving ceramide content in the skin.